The commercial supply of fluids or liquids via piping, either to industry or the domestic population is generally involved in the supply of a commodity on which industry or the domestic market rely. Accordingly, the maintenance involved in such piping work can result in considerable disruption to the supply of the fluid or liquid commodity and it is highly desirable to expedite such maintenance operations, thereby minimising disruption and down-time to said piping supplies. A particular example of such piping systems is the town supply of mains water which provides potable water to households and light industry from reservoirs via pumps and a network of underground piping.
The piping is generally configured as a branching network of pipes that diminish in dimensions ending with the street mains water pipes of about 100 mm diameter running down and along suburban streets, past households and into which a plurality of individual households can tap.
At the street level, the mains water pipes are provided with closeable gates at regular intervals every kilometer or so, to allow sections of pipeline to be isolated so as to allow maintenance thereof. However, the number of gates provided only allows isolation of a relatively large area which may affect up to 50 or so households. Accordingly, in the situations where considerable maintenance is required, the disruption to such a large number of households can be considerable and may involve health issues.
The mains water piping whilst principally provided for the supply of household water, also functions for emergency water supplied by way of fire hydrants or fire plugs, many of which are fitted at regular intervals along the street front and allow emergency access to mains pressure water by fire fighters. Fire hydrants are generally installed at regular and frequent intervals along the mains water supply piping such that a plurality of fire hydrant access points exist between any two or more isolation gates in the mains water system. The fire hydrants are connected to a generally horizontal supply of piping with a short generally vertical riser forming a tee junction with the supplied piping. This riser is then usually joined to a suitable connecting means such as a male threaded pipe section via a gate valve or other type of control valve. It would be very desirable if such fire hydrant access points could be utilised to shut off the mains water supply by acting as a temporary isolation gates. This would be particularly advantageous as the frequency of hydrants would allow a relatively small number of households to be affected by mains water pipe maintenance if such hydrant points could be used to isolate a section of mains water piping. Unfortunately, the equipment available to date, does not generally allow the ready access and occlusion of a fluid or liquid piping at a given diameter, via an access point or aperture formed in said piping which is of less diameter than the diameter of the piping to be occluded. Furthermore, the available devices are either adapted for use with gaseous fluids only of limited pressure, are non reusable or unable to be used in conjunction with hydrant access points. The provision of such a device adapted for insertion into a mains water pipe against the normal water pressure, particularly if such a device could allow insertion through an aperture and subsequent occlusion of a pipe of two or more sizes greater than said aperture would be highly advantageous and would of course allow fire hydrants to be used as access points for mains water piping.